1. Field of the Invention
The present invention relates to a camera indicating apparatus, particularly for producing an alarm signal indicating abnormal brightness and, at the same time, for indicating that the shutter is open.
2. Description of the Prior Art
Of the various light measuring systems for a camera, the so-called auxiliary aperture light measuring system has an accuracy almost as great as that of the TTL light measuring system of a single lens reflex camera.
Such an auxiliary light measuring system utilizes an auxiliary opening member coupled to the principal opening member in front of the film surface, but arranged outside of the optical axis of the principal opening member. In such a system, the amount of light coming from the object through the auxiliary opening member is considered the equivalent of the light coming from the object through the principal opening member and incident upon the film surface. The auxiliary opening member is a member which maintains a predetermined opening (hereinafter called the pre-opened state) during the light measuring mode, is totally closed when the mode is changed to the exposure mode, and then is gradually opened until it is fully open, at which position it remains during exposure.
Abnormal brightness conditions can easily be indicated with such auxiliary aperture light mechanisms by using an indicating element which responds to the output of a light sensing element arranged behind the auxiliary opening member. It is also possible easily to indicate that the shutter is open by using a second indicating element that responds to the output of the aforementioned light sensing element during an exposure control operation. This second indicating element can then be extinguished by a shutter closing signal that occurs when the shutter closes.
However, it has been impossible to indicate such an alarm signal and an open-shutter indicating signal with one indicating element when using such an auxiliary aperture light measuring system.
As mentioned, the auxiliary opening member arranged ahead of the light sensing element assumes a totally open state after the camera has changed from the light measuring mode into the exposure mode. This allows more light to strike the light sensing element than in the pre-opened state so that the low brightness alarm signal produced during the light measuring mode, and indicating that the object brightness is low, disappears the moment the mode is changed into the exposure mode. As a result, it is not possible to indicate termination of the shutter opening with a single indicating element.
Moreover, if the object brightness is high, the aforementioned auxiliary aperture system temporarily assumes the totally closed state when the mode is changed from the light measuring mode into the exposure mode. This interrupts the incidence of light on the light measuring element. Hence, the brightness alarm signal produced in the light measuring mode and indicating that the object brightness is high, disappears in a moment. As a result, erroneous alarm information is indicated at the time of the mode changeover. Thus, in both of these cases, it has been impossible to indicate the aforementioned two signals by means of only a single indicating element.
Further, in case, on the other hand, the object brightness is high, the above-mentioned auxiliary aperture means temporarily assumes the totally closed state when the mode is changed over out of the light measuring mode into the exposure mode, so as to interrupt the incidence of the light upon the light measuring element, whereby the high brightness alarm signal produced in the light measuring mode and indicating that the object brightness is high disappears in a moment, with the result that an erroneous alarm information is indicated at the time point of the mode change over. Thus, in both of the above two cases it has been impossible to indicate the above-mentioned two signals by means of only one indicating element.